The long term goal of this project is to understand the biological and biochemical properties of epidermal stem cells. During this granting period we will use a combination of light and transmission electron microscopy, autoradiography, cell culture, biochemical and immunological techniques to study this problem using monkey palm epidermis as a model system. In collaboration with Dr. Tung-Tien Sun of the New York University School of Medicine, we will: 1) assess the proliferative status of the monkey palm epidermis using metaphase arrest techniques; 2) examine whether the non-serrated basal keratinocytes, the presumptive epidermal stem cells, increase their proliferative rate during wound healing; 3) determine whether the non-serrated basal keratinocytes are slow cycling; 4) determine whether the non-serrated basal keratinocytes have a great potential for cell division (i.e., are clonogenic) in cell culture; 5) study the involvement of epidermal stem cells in the initiation and promotion phases of tumorigenesis; 6) analyze the keratins of the non-serrated basal keratinocytes to define their differentiated state; and 7) characterize the surface features of non-serrated basal keratinocytes using lectins and monoclonal antibodies prepared to the cell surface components of non-serrated basal keratinocytes and epidermal cells of other differentiated compartments. Information obtained from these studies should lead to a better understanding of the roles of epidermal stem cells in growth control, differentiation, diseases of epidermal hyperproliferation (eg. psoriasis) and carcinogenesis. This will ultimately increase our knowledge on the structure and function of skin in man and other primates.